To convey information to a viewer, head-up display (HUD) systems have been used to display or “fade” images representing information into the windshield of the vehicle, thus reducing the need for a driver or pilot to turn attention away from the road to be driven on or the air space to be flown in. Head-up display systems are often incorporated into aircraft cockpits for pilots to monitor flight information. More recently, HUD systems have been used in automotive vehicles such as cars, trucks, and the like. The HUD generally is positioned so as to reduce the viewer's need to glance downward to the vehicle dashboard and/or away from the viewing area in front of the vehicle. Thus, a head-up display (HUD) system for use with an automotive vehicle is a visual display arrangement that displays information to a viewer in the form of a virtual image, typically situated in space above the hood of the car, so that the viewer can view the road and objects outside the vehicle around and through the display along with the display itself.
In some current configurations, a projection display is situated behind the steering wheel and creates the image that projects light onto the windshield, which then reflects the light towards the driver. More particularly, a head-up display system generally includes a display projection system, a collimator, and a combiner. The projection system includes a light source that projects operating information through the collimator, which generally aligns the projected light rays. The collimated light is then reflected off the combiner, which is in the vehicle operator's field of view. In so doing, vehicle information such as, for example, fuel information, vehicle speed, and/or the like, may be displayed within the viewer's field of vision through the windshield and may permit the operator to more safely maintain eye contact with the road and other objects outside the vehicle, while also viewing the displayed information. The reflected images of the display may be focused at a position anywhere from immediately in front of the vehicle to optical infinity.
Unfortunately, current head-up display systems suffer from certain disadvantages. For example, to create a single image substantially free from ghosts, the windshield may reflect an image or light rays at a single surface with reduced (or no) reflection from all other surfaces. Laminated windshields have been used as the combiner in conventional head-up display systems to reflect primary display images. However, a secondary image is reflected off of the outer surface of the windshield (surface 1). This secondary image is superimposed over, but offset from, the primary image and thus reduces the overall image clarity, creating ghosting. In other words, conventional windshields suffer from a drawback in that they reflect off both the front and back surfaces with substantially equal efficiency.
One method of attempting to avoid multiple images involves creating a wedge in the windshield, which thereby superimposes the two images formed by the two reflections. This approach is disclosed in U.S. Pat. No. 6,636,370, the entire contents of which is hereby incorporated herein by reference. Although this approach may be effective with low-resolution images, it unfortunately does not maintain sufficient image registration over the entire viewing pupil for higher resolution images.
A similar approach involves angularly offsetting the outer major surfaces of the laminate within a first portion such that an image from the image projector source projected onto a first major surface of the laminate within the first portion is reflected in a manner that reduces double imaging of the reflected image. This approach is disclosed in U.S. Pat. No. 7,060,343, the entire contents of which is hereby incorporated herein by reference. To accomplish the offset, a special polymer-based interlayer is used. In particular, the polymer-based interlayer is a polyvinyl butyral known as wedge vinyl. The thickness of the wedge vinyl varies across a vertical cross-section of the windshield so that the surfaces of the glass substrates are no longer parallel or substantially parallel to one another. By using an appropriate angle, it is possible to re-align the two pictures coming from the first and fourth surfaces of the windshield, and the image becomes clearer.
Unfortunately, this approach is problematic for several reasons. For example, vehicles often have different windshields with different inclination angles and thus require different offset angles. As such, corresponding optical modeling and custom designs are needed for each particular design. Additionally, wedge PVB is much more expensive than standard PVB. Indeed, wedge PVB has been found to be, on average, about 6-7 times more expensive than standard PVB.
Thus, it will be appreciated that there is a need in the art for an improved head-up display and/or windshield for use with the same, that overcomes one or more of these and/or other disadvantages.
In certain example embodiments of this invention, a head-up display system for a vehicle is provided. A windshield includes first and second substantially parallel spaced-apart substrates sandwiching a polymer-inclusive interlayer, and an anti-reflective coating provided on a surface of one of the first and second substrates. An image source is configured to direct light rays corresponding to an image to be formed at the windshield. At least some of the light rays are optically removed or blocked via the anti-reflective coating. The first substrate is closest to the vehicle exterior and the second substrate is closest to the vehicle interior.
In certain example embodiments, a windshield for a vehicle for use with a head-up display system is provided. First and second substantially parallel spaced-apart substrates sandwich a polymer-inclusive interlayer. An anti-reflective coating is provided on a surface of one of the first and second substrates. The anti-reflective coating is arranged so as to optically remove or block at least some light rays produced by an image source of the head-up display system so as to reduce the occurrence of multiple images being produced by the image source. The anti-reflective coating is provided on a surface of the first or second substrate opposite the polymer-inclusive interlayer.
In certain example embodiments, a method of making a head-up display system for a vehicle having a windshield is provided. First and second substantially parallel spaced-apart glass substrates are provided. The first substrate is closest to the vehicle exterior and the second substrate is closest to the vehicle interior. A polymer-inclusive interlayer is provided between the first and second glass substrates. An anti-reflective coating is provided on a surface of the first or second glass substrate opposite the polymer-inclusive interlayer. The first and second glass substrates are laminated together using the polymer-inclusive interlayer in forming the vehicle windshield. An image source is configured to direct light rays at the windshield. The anti-reflective coating is arranged so as to optically remove or block at least some of the light rays from the image source.
In certain example embodiments, a method of forming an image in connection with a head-up display system for a vehicle having a windshield is provided. The windshield comprises first and second substantially parallel spaced-apart substrates sandwiching a polymer-inclusive interlayer, and an anti-reflective coating provided on a surface of one of the first and second substrates. An image source is configured to direct light rays at the windshield. Light rays are directed at the windshield from the image source to form the image. The anti-reflective coating is arranged so as to optically remove or block at least some light rays produced by the image source so as to reduce the occurrence of multiple images being produced by the image source. The anti-reflective coating is provided on a surface of the first or second substrate opposite the polymer-inclusive interlayer.
The features, aspects, advantages, and example embodiments described herein may be combined to realize yet further embodiments.